The invention relates to a lamp of the type having a protective sleeve of quartz surrounding a light source, in particular a metal halide arc tube.
Protective sleeves of quartz or other transparent material able to withstand operating temperatures are commonly utilized around metal halide arc tubes, also known as high intensity discharge or HID arc tubes, in order to provide protection against non-passive failure during lamp operation. These sleeves act to slow or stop fast moving arc tube fragments and prevent the rupture of the outer lamp envelope. These sleeves may also provide other functions including, but not limited to, reduction of the UV output of the lamp.
These sleeves are typically mounted around the arc tube using additional straps or clips around the outside or in the ends of the sleeve. In the case of quartz metal halide lamps, any metal supports used in the mounting must be kept away from the arc tube or be electrically floating to reduce the rate of sodium loss. An arrangement of this type is disclosed in EP 0 784 334.
Protected mount designs are typically quite expensive and difficult to mechanize. In addition, most mounts are insufficiently rigid and may come apart with rough lamp handling (as during transportation).